Electron tube



G. J. EKKERS ELECTRON TUBE July 17, 1962 Filed Sept. 5, 1958 a FIG-lFIG'Z INVENTOR. Gysberii Jacob Ek/fers BY PM JW 29 J /Jew I Afiior-neysUnited States Patent 3,045,142 ELECTRON TUBE Gysbert Jacob Elihers,Wettingen, Switzerland, assignor to Patelhold Patentverwertungs- &Elelrtro-Holdiug A.G., Glarus, Switzerland Filed Sept. 5, 195a, Ser. No.759,271 Claims priority, application Switzerland Sept. 7, 1957 Claims.((31. 313-251) The present invention relates to electron tubeconstruction and more particularly to an arrangement for exerting atensile stress upon a plurality of electrode members within the tubesuch as the cathode and control grid. Longitudinal stressing of theelectrode members is advantageous in that it serves to minimize bendingor breakage of the electrodes or some of their parts due to the heatingelfect which arises as a result of operation of the tube. Moreover, byapplying tensile stress to one or more of the electrodes, it enables thetube designer to establish a correspondingly smaller radial distancebetween the cathode and control grid, which is highly desirable forvarious known technical reasons.

The objective of the invention, namely application of tensile stress tothe electrode members of the tube is attained, generally speaking, bymounting one end of each of the electrode members in fixed positioninside the wall of the tube, the electrode members being disposed inradially spaced relation and extending in a direction longitudinally ofthe tube axis, and mounting the opposite end of each electrode member ona support member which is arranged for movement longitudinally of thetube axisin a direction away from fixedly mounted end of the electrodemember under the action of a loading spring.

More particularly, the improved construction comprises a first tubularmember which is fixed in position and extends longitudinally of the tubeaxis, i.e. the electrode system axis, an elongated member such as a rodmounted for displacement within and longitudinally of the first tubularmember, a first electrode support member connected to the upper end ofsaid rod, a first electrode member extending longitudinally of said tubeaxis, the lower end of said first electrode member being fixed inposition and the upper end thereof being connected to said firstelectrode support member, and a first spring under compression andhaving the lower end thereof in abutment with the lower end of saidfirst tubular member and the upper end thereof pushing upwardly againstthe lower end of said rod to thus apply tensile stress to the firstelectrode member; a second tubular member surrounding said first tubularmember and mounted thereon for longitudinal displacement, a secondelectrode support member connected to the upper end of. said secondtubular member, a second electrode member extending longitudinally ofsaid tube axis, the lower end of said second electrode member beingfixed in position and the upper end thereof being connected to saidsecond electrode support member, and a second spring under compressionand having the lower end thereof bearing against a fixed abutment andthe upper end thereof pushing up- Wardly against the lower end of saidsecond tubular memher to thu-s apply tensile stress to the secondelectrode member.

The invention will become more apparent from the following detaileddescription of one practical embodiment thereof, and from theaccompanying drawings.

FIG. 1 of these drawings shows the improved electrode mounting structurein vertical central section, the other structural parts of the electrontube not essential to an understanding of the invention being excludedin the interest of simplifying the disclosure.

FIG. 2 is a transverse section on line 22 of FIG. 1.

3,045,142 Patented July 17, 1962 FIG. 4 is also a transverse section online i-4- of 7 FIG. 1 and also drawn to a larger scale.

With reference now to the drawings it will be seen that the improvedconstruction for applying tensile stress to the electrode memberscomprises a first cylindrical tubular member 1 which can be made ofmetal arranged concentric about the axis of the electrode system withinthe tube. The lower end of tubular member 1 is closed and is fixed tothe base plate 2 of the tube by being inserted in a suitable recess insuch plate. The upper end of tubular member 1 is open. Arrangedconcentrically within the tubular member 1 is an elongated member 3which can be in the form of a round metallic rod as shown. The rod 3 isprovided at its upper and lower ends with cylindrical members 4 and 5,respectively and which are made of electrically insulating material, andthe outer diameters of the cylindrical members 4 and 5 are made justslightly less than the internal diameter of tubular member 1 as willestablish a close sliding fit therebetween. Mounted atop the upper endof the rod 3, i.e. at the top of the cylindrical member 4 is a circularor star-shaped disc 6, the plane of the disc being normal to the tubeaxis, and secured to the periphery of disc 6 is the upper end of thecontrol grid '7, the individual conductors of which extend parallel tothe tube axis and lie on a circular cylinder.

A second cylindrical tubular member 8 which can also be made of metalsurrounds the first tubular member 1 and is spaced radially therefrom.This second tubular member 8 is concentric with tubular member 1 andextends longitudinally of the same but is somewhat shorter than tubularmember 1. Positioned within and secured to the upper and lower ends ofthe second tubular memher 8 are flanged sleeves 9 and 10, respectivelyand which are also made of electrically insulating material. Theinternal diameters of the sleeves 9 and 10 are made just slightly largerthan the external diameter of the second tubular member 8 as will alsoestablish a close sliding fit therebetween. Mounted atop the upper endof tubular member 8, Le. at the top of the upper insulating sleeve 9, isan annular disc 1'1 which surrounds the first tubular member 1, theplane of th s disc also being normal to the tube axis, and secured tothe periphery of disc 11 is the upper end of the cathode 12, theindividual conductors of which extend parallel to the tube axis and lieon a circular cylinder which is located radially within the circularcylinder that contains the wiresor conductors of the control grid 7.

Located within the bottom of the tubular member 1 is a first helicalspring 13 under compression. The lower end of spring 13 bears againstthe lower closed end Wall of tubular member 1, and the upper end ofspring 13 bears against the lower end of insulating member 5 thusexerting a constant upward force against member 5 and hence rod 3 andalso the disc '6 which thereby exerts an upward pull on the conductorswhich form the control grid 7, the lower end of the latter being securedto a ring 15 which surrounds the tubular member 8 in radially spacedconcentric relation and is fixed in position within the electron tube.Thus the control grid conductors 7 are placed under the desired tensilestress.

A second helical spring 14 under compression surrounds the lower end oftubular member l. The lower end of spring 14 bears against the baseplate 2, and the upper end of spring 14 bears against the lower endflange of the bottom insulating sleeve 10 thus exerting a constantupward. force against this sleeve and hence also tubular member 8 andalso disc 11 which thereby exerts an upward pull on the conductors whichform the cathode 12, the lower end of the latter being secured to a ring16 which also surrounds tubular member 8 in radially spaced concentricrelation and is fixed in position within the eleetron tube. Thus theconductors which form the cathode 12 are also placed under the desiredtensile stress.

In order to prevent any undesired torsional effect between the cathodeand control grid as a result of forces which arise due to operation ofthe tube, means can be; provided for preventing any relative rotationbetween the discs 6 and 11. One practical way in which this result canbe obtained is to provide the outer surface of the tubular member 1 witha longitudinally extending groove 17 which receives a longitudinallyextending rib 18 provided on the inner surface of the sleeve 9 as shownin FIG. 3, and to similarly provide the inner surface of tubular member1 with a longitudinally extending groove 19 which receives alongitudinally extending rib 20 provided on the outer surface of thecylindrical member 4 as shown in FIG. 4.

This expedient prevents any relative rotation between the first andsecond tubular members 1 and 8, and also prevents any relative rotationbetween the first tubular member 1 and the cylindrical member 4. Thusthere can be no relative rotational displacement between the discs 6 and11.

In conclusion, it is to be understood that while I have described andillustrated one practical embodiment of my invention, variousmodifications in the construction and arrangement of component parts maybe made without, however, departing from the spirit and scope of theinvention as defined in the appended claims.

I claim:

1. A device for supporting electrode members of an electron tubecomprising a first tubular member fixed in position within said tube andextending upwardly along the tube axis, a rod member mounted within saidfirst tubular member for longitudinal displacement, a first electrodesupport member supported by said rod member, a first electrode memberextending longitudinally of said tube axis, the lower end of said firstelectrode member being fixed in position and the upper end thereof beingconnected to said first electrode support member, and a first springunder compression within said first tubular member, the lower end ofsaid first spring being fixed as to position and the upper end thereofpushing upwardly against the lower end of said rod member to thus applytensile stress to said first electrode member; a second tubular membersurrounding said first tubular member and mounted thereon forlongitudinal displacement, a second electrode support member connectedto the upper end of said second tubular member, a second electrodemember extending longitudinally of said tube axis, the lower end of saidsecond electrode member being fixed in position and the upper endthereof being connected to said second electrode support member, and asecond spring under compression and surrounding said first tubularmember, the lower end of said second spring being fixed as to positionand the upper end thereof pushing upwardly against the lower end of saidsecond tubular member to thus apply tensile stress to said secondelectrode member.

2. An electrode supporting device as defined in claim 1 wherein thelower end of said first tubular member is closed and the lower end ofsaid first compression spring bears against said closed end.

3. An electrode supporting device as defined in claim 2 wherein thelower closed end of said first tubular member is mounted on a base plateand the lower end of said second spring bears against said base plate.

4. An electrode supporting device as defined in claim 1 and whichfurther includes means preventing relative rotation between said rod andfirst tubular member, and means preventing relative rotation betweenfirst and second tubular members thus to prevent any relative rotationaldisplacement between said first and second electrode support memberswhich are connected to the upper end of said rod and second tubularmembers respectively.

5. An electrode supporting device as defined in claim 1 wherein said rodmember includes cylindrical members of electrically insulating materialat the opposite ends thereof establishing a sliding fit with the innersurface of said first tubular member and wherein said second tubularmember includes flanged sleeve members disposed within opposite endsthereof establishing a sliding fit with the outer surface of said firsttubular member.

References Cited in the file of this patent UNITED STATES PATENTS2,399,004 Crawford Apr. 23, 1946 2,542,639 De Walt Feb. 20, 19512,617,056 Dailey et al. Nov. 4, 1952 2,737,611 Crapuchettes Mar. 6, 1956

